The fundamentally largest change from Kubrick to K2 is in how the template deals with plugins. For a while Kubrick shipped with a few plugins and some scruffy code, which people could uncomment if they wanted plugin support. Bad mojo.
K2 automatically detects a range of my favorite plugins out of the box, and will upon detecting set them up for you, no hassles. I try to keep an eye on the whole plugin market, but feel free to mail me about your favorite plugins so that I might give them a spin.
Also, K2 will have a configuration file in which you can toggle between two-column or single-column layout, as per popular request.
Other than that it’s getting some nips and tugs here and there and all around; oh, and it is now entirely CSS driven. No more images needed